Storage devices are often used to record data on or to reproduce data from a recording media. A storage device can include a rotating magnetic disk as one type of recording media. In addition to a magnetic disk, a storage device can include a second type of recording media, such as a solid state, non-volatile memory. Storage devices including both a disk and a solid state non-volatile memory may be referred to as a hybrid drive.
The storage device industry is always trying to increase the recording density of the disk, or in other words, the amount of data that can be stored in a given area on the disk. Shingled magnetic recording (SMR) has recently been introduced as a way of increasing the number of tracks per inch (TPI) by making the tracks narrower. Since it is technologically easier to read narrow tracks than to write narrow tracks, SMR increases TPI by using a relatively wide write head with a stronger magnetic field to overlap tracks like roof shingles. The non-overlapping portion then serves as a narrow track that can be read by a narrower read head.
Although a higher number of TPI is ordinarily possible with SMR, the overlap in tracks can create a problem when writing data since new writes to a previously overlapped track affects data written in the overlapping track. For this reason, tracks are usually sequentially written to avoid affecting previously written data. Such sequential writing can create new data management issues not addressed in conventional storage devices.